The present invention relates to differential gear assemblies and, more particularly, to multi-pinion differential gear assemblies.
When a differential gear assembly is required to have only a moderate torque transmission capability, a two pinion gear system will generally be utilized and perform satisfactorily. In a two pinion gear system, generally there is a single shaft which mounts the two opposing pinion gears in meshing engagement with and between a pair of side gears.
When a differential gear assembly is required to transmit a substantially increased amount of torque, generally a four pinion gear assembly is generally required. The four pinion gear assembly distributes the torque over the four pinion gears to reduce tooth stress load on the gears. In a four pinion gear system, generally there are two shafts which mount the two opposing pairs of pinion gears in a meshing arrangement between a pair of side gears. While the four pinion gear system transmits increased torque, there is a difficulty in assembling the four pinion differential gear assembly by automated processes.
Four pinion gear differential gear assemblies generally require a pair of shafts and a split casing to enable the four pinion gears to be assembled into the casing. This is a very labor intensive operation and adds a significant cost to the manufacturing of the four pinion differential gear. Also, the split casings are prone to misalignment during assembly.
Accordingly, there is a need in the field for a four pinion differential gear assembly which may be easily assembled by automated processes. The present invention provides the art with such a device.
The present invention provides the art with a differential gear assembly having a unitary shaft mechanism which maintains all pinion gears thereon enabling simultaneous insertion of all the pinion gears into the differential gear casing. The present invention provides the art with a differential gear casing which includes elongated slots which mount the shaft mechanism along with providing lubrication access into the differential casing to lubricate the side and pinion gears therein. The casing also provides the art with an abutting surface which supports spherical thrust washers which provide bearing surfaces The abutting surface has a substantially spherical curvature which lends itself to be manufactured by an uninterrupted machining operation. Also, a multi-pinion gear assembly is provided which enables the pinion gears to center within the differential gear seeking their own backlash
From the following detailed description taken in conjunction with the accompanying drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.